Electrical control circuit



April 7, 1953 P. GLASS ELECTRICAL CONTROL CIRCUIT Original Filed July12, 1945 Qct Q Six INVENTOR. PM GZQSS, M W aw I l l I I I I I I l I I Il I I I I I I l I L- Patented Apr. 7, 1953 ELECTRICAL CONTROL CIRCUITPaul Glass, Chicago, Ill., assignor to Askania Regulator Company, acorporation of Illinois Original application July 12, 1945, Serial No.604,656, now Patent No. 2,493,130, dated January 3, 1950. Divided andthis application June 8, 1949, Serial N0.;97,893

Claims.

The-invention relates generally to electrical control circuits and moreparticularly to control 7 form.

Y Heretofore circuits of the character described have depended largelyupon electron tubes for accomplishment of the ends sought, necessitatingcomplicated circuits or excessive numbers of stages of amplificationwith the resultant disadvantages of high cost, operational andmaintenance difficulties and, above all, the disadvantage that thecontrolling portion of the circuit 'was not completely independent ofthe controlled portion so that reaction in the controlled portion mightreflect into the controlling portion with possible resultant injurythereto.

It is an object of this invention, therefore, to provide a new andimproved circuit for the amplification or modification, or both, of asignal or for the utilization of a small signal in the control ofsubstantially larger power application.

Another object of the invention is to provide a new and improvedelectrical control circuit adaptable to respond to alternating currentsignals and adaptable to produce either direct or alternating current.

Another object is to provide a new and im-- proved circuit of thecharacter described having an electron tubeless, main amplification orcontrol stage and an input signal circuit in advance "of the main stageconditioning the signal by modification and possibly also amplificationfor use in connection with the main stage;

A further object is to provide a control circuit, including saturablereactors, which will function in response to an A. C. signal to producea D. C.

output of a given magnitude independent of the magnitude of the signalbut varying in sign with the phase of the signal.

Yet a further object is to provide a control circuit, includingsaturable reactors, which will function in response to an A. C. signalto produce an A. C. output of a given magnitude independent of themagnitude of the signal, the output being at one or the other of twooutput stations dependent upon the phase of the signal.

Other objects and advantages will become ap parent from the followingdetailed description taken in connection with the accompanying drawings,in which:

Fig. l-is a box-type diagrammatic illustration of a circuit embodyingthe features of this invention.

Fig. 2 is a circuit diagram illustrating in detail a possibleconstruction that the units represented by the rectangles in Fig. 1 maytake.

Fig. 3 is a diagram illustrating the characte of the output of the firstunit of the circuit.

Fig. 4 is a diagram illustrating the character of the output of thesecond unit of the circuit.

Fig. 5 is a diagram illustrating the character of the output of thethird or final unit of the circuit. r

This application is a division of my application Serial No. 604,656,filed July 12, 1945, now Patent No. 2,493,130, issued January 3, 1950.

While the invention is susceptible of various modifications andalternative constructions, it is herein shown and Will hereinafter bedescribed in a preferred embodiment. It is not intended, however, thatthe invention is to be limited thereby to the specific constructiondisclosed. On the contrary, it is intended to cover all modificationsand alternative constructions falling within the spirit and scope of theinvention as defined in the appended claims.

Generally speaking, the invention contemplate the provision of a new andimproved circuit wherein a small electrical signal is utilized to governsubstantially larger power applications or where the signal is amplifiedor modified, possibly both, for subsequent use in its new form. In sucha circuit the input is a controlling signal while the output is acontrolled signal regardless of whether the latter is of a magnitudecommonly referred to as a signal or is of such a magnitude as to be, oris in fact, the operating energy for an electrical device such as amotor or the like. To that end, the circuit is composed generally ofmeans for modifying and possibly amplifying the controlling or thecontrolled signal, and means functioning as the main amplifying orcontrol means.

Herein the circuit is composed generally of three subcircuits or circuitunits or portions A, B and C. Of these units, A is the main amplifyingor control means or circuit and functions to have an alternating currentoutput controlled as to magnitude and sign by the controlling or inputsignal, but having an independent power source so that the absolutepower output is not limited by the power of the signal source. Unit B isthe control signal receiving unit. This unit usually functions toamplify the signal but, above all, it modifies the character of thesignal so as first to obtain a signal of a character suitable for usewith unit A, and, secondly, to obtain a signal of such character as toresult in an output of a character desired. Herein the signal is sosaturation of the core 20.

modified as to have an on or ofi characteristic, 1. e., the modifiedsignal is either zero or a certain maximum value regardless of themagnitude of the input signal. Unit C is also a modifier of the signalwhich it receives, though herein the function of unit C is always thatof a rectifier converting the A. C. output of the unit A to a D. C.output. The term direct current or its abbreviation D. C., as hereinemployed to designate the output of the units C and B and the controlcoils of the unit A, is used in the broad sense of that term, i. e., asopposed to alternating current and as including pulsating current suchas produced by a generator or rectifier and not in the limited senseonly of absolutely continuous, pulse-free current such as produced by achemical cell under constant load.

As the description proceeds it will become apparent that by appropriateconstruction of the unit B and by use or elimination of the unit C theinvention may be employed to obtain either an A. C. or a D. C. output.More-over, by the employment of an A. 0. signal receiving unit B of thecharacter hereinafter described, the circuits embodying the concept ofthis invention may be employed to obtain an A. C. output which is eitherzero or some definite magnitude regardless of the magnitude of the inputsignal, and similarly a D. C. output may be obtained which also iseither zero or some definite magnitude regardless of the magnitude ofthe input signal. In the case of the A. C. output this is herein madeavailable at one or the other of two stations dependent upon the sign orthe signal. In the case of the D. C. output, the sign thereof iscontrolled by the sign of the input signal. The meaning of the term signas applied to D. C. signals or output is, of course, the customarymeaning and hence will be understood. The meaning herein of the termsign as applied to an A. C. signal or output is that of 180 phasedisplacement. Thus circuits ombodying the concept of this invention maybe employed to obtain an A. C. or a D. C. output of definite andconstant value from an A. C.

input signal of varying magnitude, the sign or the D. C. output in bothinstances varying with the sign of the input signal and the A. C.output. being controlled as to output station by the sign of the inputsignal. In speaking of A. C. or D. C. currents or outputs, average andeiiective and not instantaneous values or magnitudes are intended.

Turning now to a consideration of the more detailed embodiments of theinvention, the unit A will first be described. This unit, as alreadystated, is the main amplification stage and control unit or subcircuitand accomplishes control of the magnitude of the output and itsavailability at one or the other of two stations in accordance with themagnitude and sign of the signal without the employment of electrontubes. The unit A comprises a pair of saturable reactors represented bythe broken-line rectangles l5 and H5. The saturable reactor i5 iscomposed of. a pair of A. C. coils l7 and i8 and of a D. C. or controlcoil 9. All of the coils are wound on a common iron core 29 in suchmanner that current flowing in the coils I? and i8 will not inducecurrent or voltage in the D. C. coil i9, while flux produced by directcurrent flowing in the D. C. coil [9 will vary the impedance of the A.C. coils I! and 18 by Varying the degree or The reactor is further sodesigned that the coils I1 and is have a very high impedance when nocurrent is flowing in the D. C. coil [9. Necessarily the reactor andparticularly the coils thereof must be designed with a View to thevoltages with which it is to be employed, with the coils I! and It beingcapable of taking substantially the full applied voltage when no currentis flowing in the D. C. coil IS. The saturable reactor [6 is identioalwith the reactor [5 and comprises A. C. coils El and 22 and a D. C. orcontrol coil 23, all wound on a common iron core 24.

The unit A sometimes hereinafter referred to as the saturable reactorcircuit is completed by an A. C. supply circuit comprising power supplyleads. 25 and 26., adapted to be connected to an A. C. po.wer sourcerepresented at 21, and two output stations herein represented by pairsof terminals 28 and 29, the unit A thus being adapted for the connectionthereto of two loads. The A. C. coils of the saturable, reactors are soconnected in the supply circuit that one of the pairs of terminals 28,29 will be subjected to substantially the full potential of the powersource while the other will have small or negligible potential,depending upon which of the reactors has its control coil energized atthe time. To that end, the saturable reactors, that is, the A. C. coilsthereof, are connected in separate yet interconnected circuits eachhaving the A. C. coils of one reactor, the terminals representing onestation, and the A. C. power source in series, with the power sourcecommon to the two circuits. Herein the terminals 28 are connected inseries with the coils H and is of the saturable'reactor i5,'the coilsalso being in series, and the terminals 2% are in series with the coils2i and 22 of the saturable reactor 15, the coils again being also inseries. Inasmuch as the saturable reactors are designed so as to becapable ofv taking substantially the full applied voltage of the powersource 27 when the control coils l9 and 23 are not energized, it followsthat energization of one or the other of the control coils l9. and 2.3will determine which of the pairs of terminals 28 and 29 will have sucha small voltage applied thereto as to be incapable of energizing a loadconnected to the terminals and which of the terminals on the other handwill have an effective potential.

In the embodiment of the invention shown for purposes of disclosure, thecircuit is adapted to respond to an A. C. input or control signal.Accordingly, there is illustrated, by way of example, a unit B which isoperable to receive an A. C. signal, amplify the, same to a magnitudesuitable for use in connection with the saturable reactors l5 and i6,and at the same time, modify the signal to give it a desiredcharacteristic and cause energization of one or the other of the D. C.coils l9 and 23, depending upon the sign (phase) of the input signal,but never both coils simultaneously for any material period of time.Herein the unit B is of such character that an input signal will causeenergization of the D. C. coils l9 and 23, as shown in Fig. 3, whereinthe line it represents the current flowing in the coil !9 and 2'2represents the current flowing in the coil 23. In other words, so longas the input signal is and remains zero the current in each of the coilsi9 and 23 will also be zero. With an increase in the signal magnitude,regardless of how small, that is, with any signal of a magnitude otherthan zero, the current in onelc o il will remain at zero while thecurrent in the .other coil will jump to some definite and constant-magnitude as represented in Fig. 3. As will presently be more fullymade known, once operation of the unit B has been initiated, one or theother of the coils i9, 23 will be energized even when the signal returnsto zero. Which of the coils I 9 or 23 will be energized and which willbe deenergized will, however, be determined by the sign of the inputsignal. Note that the unit B as to the individual coils I9 and 23 has anoff or full-on characteristic and as to the unit as a whole has whatwill result in a load selection characteristic at an intermediate stagein the circuit and a sign controlling characteristic in the final outputof the circuit.

While a unit B capable of producing currents in the coils I9 and 23 ofthe character described might take a variety of forms, one such unit isshown in Fig. 2, it being understood that the showing is exemplary onlyand that a variety of other subcircuits might be employed and that, inparticular, it might prove necessary to have more than one stage toproduce the amplification of the signal required to provide directcurrents of a magnitude suitable for control of saturable reactors.Herein the unit 33 or signal input circuit comprises a pair of gridcontrolled, gaseous tubes 96 and SI, each having a plate 92, a cathode93 and a grid 9 3. The tube 9!) has a plate circuit, generallydesignated $5, having therein the D. C. coil I9 of the saturable reactorI5. The tube 9! has a plate circuit, generally designated 95, which hasconnected therein the D. C. coil 23 of the saturable reactor It. Theplate circuits of the tubes 98 and 9! have a common lead 9'! adapted forthe connection therein of an A. C. voltage source, represented at 98,providing the plate voltage for the tubes. If desired, each of the platecircuits includes a condenser 99 connected In parallel with the D. C.coil and operating in well known manner to cause flow of unidirectionalcurrent during the negative half cycle of the plate volta e of the tubewith which the condenser is associated. The grids 94 are by leads Iflilconnected to opposite ends of a winding IUI constituting the secondarywinding of a transformer, generally designated I02, having a primarywindlng I03 connected at its ends to signal input terminals I 04 andM55. The midpoint of the secondary winding Illl is by a lead Hi6connected to the juncture of the plate circuits with the cathodes.Connected in the lead Idfi is a phase shifting means Ill! operable tovary the phase of the grid bias voltage relative to the plate voltageand herein adjusted to be substantially 180 but of phase with the platevoltage so as to prevent firing oi the tubes when no signal is present.Connected in the lead from the terminal I M to the winding :03 is acondenser I08 provided to give the signal voltage the proper phaserelationship with respect to the source for the plate voltage and phaseshifting means :01, so that the signal may be effective to control thetubes 9% and SI. A resistor Hi9 is connected in each of the leads I538.Though not here shown, it is to be appreciated that the tubes 9i] andiii are provided with suitable means for heating the cathodes 93.

As above stated, the tubes are so biased that at zero signal there is nocurrent flow in either plate circuit. A signal of any value other thanzero, making allowance, of course, for a departure sufficient toovercome the dead zone of the tubes, will cause breakdown of one or theother of "the tubes 90 and SI, depending upon the sign of fthe signal.Inasmuch as the tubes 98 and 9| are gaseous tubes, the magnitude of thesignal has no influence on the current flow through the tube where, ashere, a signal of the smallest magnitude will cause the tube to breakdown. Hence there results a D. C. output of the unit B having thecharacteristic shown in Fig. 3, namely, no current in either coil I9 or23 at zero signal and a definite and constant value of current in one orthe other coil, depending upon the sign of the signal, at any signalabove zero magnitude.

A brief description of the operation of the circuit, as thus fardescribed, may facilitate understanding of the invention andappreciation of the advantages thereof. Let it be assumed, therefore,that the input signal is zero. Under that condition, there will be noflow of current in the D. C. coils I9 and 23. The saturable reactors I5and I6 will then be at full impedance and there will be no materialdifference in potential across either pair of output terminals. Let itbe assumed further that the A. C. input signal is now increased fromzero to some definite magnitude and that the sign of the input signal issuch that the signal will lie to the right of the vertical axis of thegraph of Fig. 4. Under that assumption, tube will break down and thecurrent iI flowing in the D. C. winding I9 will jump from zero to thedefinite and constant value represented in Fig. 3, this being the fulloutput of the tube 90. The current i2 flowing in the winding 23 wilremain zero. Hence the potential difference across the terminals 29 willremain as at zero signal but the impedance of reactor I5 will be loweredand hence the potential difference across the terminals 28 will beincreased. In other words, with a load connected to each of the pair ofoutput terminals there would be output at terminals 28 but no materialoutput at terminals 29. Conversely, if the sign of the input signal isreversed and the signal then increased in magnitude as before, the tube9| will break down and current i2 flowing in the D. C. winding 23 willjump from zero to the definite and constant value represented in Fig. 3,this being the full output of the tube 9 I. With such change in sign ofthe signal, the tube 90 will cease firing and the current iI flowing inthe winding I9 will return to zero magnitude. Hence the result will bereversed with output at the terminals 29 but no output at terminals 28.It will be apparent, therefore, that there will be obtained an output ofthe character represented in Fig. 4, namely, an output which is zero atzero signal, but at any other signal magnitude has a single, definitevalue independent of signal magnitude; the output appearing selectivelyat the terminals 28 or 29 dependent upon the sign of the signal. Theoutput is thus represented by the lines III and II I in Fig. '4. Thecircuit results in control similar to that of a selector switch butobtains that control by means of an A. C. signal.

The final output of the circuit is a D. C. output of a value zero, orsome definite and constant value independent of the magnitude of theinput signal but with a sign or polarity corresponding to the sign ofthe A. C. input signal. To that end, a rectifier circuit or unit C isconnected as the loads of the saturable reactor circuit or unit A.

Herein the rectifier unit C is composed of two gaseous type, full waverectifier tubes 60 and GI each having a pair of plates 62 and 63 and acathode 54. The rectifier unit is inductively coupled to the saturablereactor circuit through the medium of a pair of transformers TI and T2each having a primary winding 65 anda. secsignal.

is connected to the terminals 29 of the saturable reactor unit A. Thetubes 56 and ii are connected to operate in such manner that the D. C.

output will be of one sign or polarity when the A. C. output is at theterminals 28, and of the opposite polarity when the A. 0. output is atthe terminals 2%. To that end, the plates 62 and 63 of the tube. 86 areby leads-5'! and 68, respectively,

connected to the ends of'the secondary winding 6510f the transformer Ti,and the plates 62 and 63 ofthe tube 55 are by leads t9 and. it,respectively, connected to the opposite ends of the secondary winding ofthe transformer The ;cathode fi l of the tubefii-l is by a lead llconnected to the midpoint of the secondary windingof the transformer T2,while the cathode of -tube 6! is by a lead '12 connected to the midpointof the secondary winding of the transformer Ti. Power output leads itare connected to the leads -'H and i2 and end in terminals '14constitutin .the D. C. output terminals to which a D. C. load ilarly,the tube 5! will fire during both the positive and the negative halfcycles of the output from the terminals 29 and thus in each instancefull wave rectified output is obtained at the output terminals is of therectifier but the polarity of the output will be reversed.

With this full wave rectification, the D. C. output of the circuit willcorrespond to the A. C. output of the saturable reactor circuit and,inasmuch as this latter output has already been sh'ownto be of an off orfull-on type and independent of the magnitude of the A. C. signal (seeFig. 4), the D. 'C. or end output of the entire circuit will also be ofan on" or full-on type and independent of the magnitude or" the A. C.input Further, with the sign of the input signal determining output atterminals 28 or 29 and .with the selective output of unit A determiningsignal input circuit having two sets of output ter- -minals and operablewith a signal of any mag- .nitude'present to'produce at one or the otheronly of the sets of terminals a direct current of constant magnitudelarger than zero and independent of si nal magnitude, the set of outputterminals at which current isproduced being determined by the Sign 01"the input signal, a pair of saturable reactors each having an A. C.

Winding and a control winding, control "windings being connected one toeach set of output terminals of said input circuit, and A. C. supplycircuit for a pair of A. C. loads comprising two pair of load terminals,a single A. C.

power source connected at one side to one terminal of each of the pairof load terminals and at the other side to one end of the A. C. windingof each reactor, the remaining end the A. C. winding of each reactorbeing connected to the remaining terminal of each pair of load terminalsso that each .-reactor controls the output to one only of the loads,andaiull wave rectifier circuit connected to form the loads for saidsupply circuit and having output terminals tor the connection of a D. C.load thereto, the output of said rectifier circuit being zero at zerooutput of said signal input circuit and at any signal magnitude causingoutput of said signal circuit being of a constant magnitude larger thanzero and independent of signal magnitude but varying in sign with thesign of the input signal.

2. An electrical control circuit comprising a signal input circuithaving two sets of output terminals and operable to produce at oneor theother only of the sets of terminals a direct current of constantmagnitude larger than zero and independent of signal magnitude, the setof output terminals at which current is produced being determined by thesign of the input signal, a saturable reactor circuit comprising a pairor saturable reactors each having an A. C. winding and a controlwinding, said control windings being connected one to each set of outputterminals of intput circuit and an A. C. supply circuit having two setsof output terminals and, a single A. C. power source common to said setsof output terminals, the C. winding of each reactor being connected inseries with one only of the sets of output terminals of said saturablereactor circuit and with said power source, and a full wave rectifiercircuit, including rectifier tubes of the gaseous discharge type,connected to said sets of output terminals to form the loads for saidsaturable reactor circuit and having a single set of output terminalsfor the connection of a D. C. load thereto, the output of said rectifiercircuit being zero at zero output of said signal input circuit and atany signal magnitude causing output of said signal circuit being of aconstant magnitude larger than zero and independent of signal magnitudebut varying in sign with the sign or" the input signal.

3. An electrical control circuit comprising a signal input circuithaving two sets of output terminals and operable with a signal of anymagnitude present to produce at one or the other only of the sets ofterminals a direct current of constant magnitude larger than zero andindependent of signal magnitude, the set of output terminals at whichcurrent is produced being determined by the sign of the input signal, asaturable reactor circuit comprising a pair of saturable reactors eachhaving a pair of A. C. coils and a control coil wound on a common core,the A. C. coils being so arranged as not to induce an A. C. voltage inthe associated control coil, said control coils being connected one toeach set of output terminals of said input circuit and a pair of A. C.supply circuits each having terminals for the connection of an A. C.load therein and having, a common A. C. power source, the A. C. coils ofeach reactor being connected in series with one another and in serieswith the load in each supply circuit only, and a full wave rectifiercircuit connected to form the loads for said supply circuit and havingoutput terminals for the connection of a D. C. load, thereto, the outputof said rectifier circuit being zero at zero output of said signal inputcircuit and at any signal magnitude causing output of said signalcircuit being of a constant. magnitude larger than zero and independentof signal magnitude but varying in sign with the sign of the inputsignal.

4. In an electrical control circuit, a signal input circuit having twosets of output terminals and having means including a pair of electrontubes of the gaseoustypeoperablewith a signal of any magnitude presentto produce at one or the other only of the sets of terminals a directcurrent of constant magnitude larger than zero and independent of signalmagnitude, the set of output terminals at which current is produced.being determined by the sign of the input sig-= nal, and a saturablereactor circuit comprising a pair of saturable reactors each having acontrol winding and an A. C. winding, said control windings beingconnected one to each set of output terminals of said input circuit, andan A. C. supply circuit having two sets of output terminals, a singlesource of A. 0. power, a lead common to said last named sets of outputterminals connected to one side of said power source, aiead common tosaid A. C. windings connector to the other side of said power source,and a lead connecting the remaining end of each A. C. windingrespectively to the remaining sides of said last named two sets ofoutput terminals.

5. In an electrical control circuit, an A. C. signal input circuitcomprising a pair of grid controlled, gaseous electron tubes each havinga plate, a cathode and a grid, a plate circuit for each of said tubesincluding a common A. C. source of plate potential, a grid circuit foreach of said tubes including a phase shifter providing 10 the grid biasfor said tubes adjusted to cause firing of a tube upon application of asignal or any magnitude and to arrest firing upon removal of the signal,and a saturable reactor circuit comprising a pair of saturable reactorseach having a pair of A. C. coils and a D. C. coil wound on a commoncore, the A. C. coils being so arranged as not to induce an A. C.voltage in the associated D. C. coil, said D. C. coils being connectedone in the plate circuit of each of said tubes and an A. C. supplycircuit having two sets of output terminals and a single A. C. powersource, the A. C. coils of each reactor being connected in series withone another and in series with one only of the sets of output terminals.

PAUL GLASS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,973,055 Fitz Gerald Sept. 11,1934 25 2,331,411 Milarta Oct. 12, 1943 2,306,998 Claesson Dec. 29, 19422,458,937 Glass Jan. 11, 1949

